Polymerase chain reaction (hereinafter, abbreviated as PCR) is a method for amplifying a particular nucleic acid sequence from a mixture of various types of nucleic acids. A particular nucleic acid sequence can be amplified by performing at least one cycle of the following steps: adding into the mixture a DNA template such as genomic DNA or complementary DNA obtained by reverse transcription from messenger RNA, two or more types of primers, thermostable enzymes, salt such as magnesium, and four types of deoxyribonucleoside triphosphates (dATP, dCTP, dGTP and dTTP) and splitting of the nucleic acids; and binding the primers to the nucleic acids; and allowing hybridization using, as a template, the nucleic acids bound by the primers and the thermostable enzymes. Thermal cycling is performed by increasing and decreasing the temperature of a reaction container used for DNA amplification reaction. There are various mechanisms for changing the temperature, including a mechanism in which the temperature of the reaction container containing a sample is changed through heat exchange using a heater, a Peltier element or hot air, a mechanism in which the temperature is changed by alternately bringing the reaction container into contact with heater blocks or liquid baths at different temperatures, and a method in which the temperature is changed by running a sample through a flow channel that has regions of different temperatures. Currently, the fastest commercially available device is, for example, Light Cycler from Roche, which has a mechanism where a specimen, DNA polymerase, small sections of DNA as primers and a fluorescent dye label for measurement are placed into each of a plurality of glass capillary tubes, where the temperatures of small amounts of droplets in the capillary tubes are shifted by blowing hot air at a temperature intended for the droplets, for example, at two temperatures, i.e., 55° C. and 95° C., while at the same time, the glass capillary tubes are irradiated with light for exciting the fluorescent dye to measure the resulting fluorescent intensity. According to these methods, the temperature of the sample can be repeatedly shifted.
Moreover, a fluid impingement thermal cycler device has been reported that controls the temperature of a specimen by impingement of fluid jet on the outer wall of the specimen-containing region (Japanese Patent Publication No. 2001-519224 (Patent Document 1)).